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Streamlines
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Actve, Opaque, Colorize | Decide about the visibility, colorizing and transparency of the streamline |
Integration Step length | The factor used to determine the minimal step length of the
Runge-Kutta method. Small values lead to high number of iteration steps within each fine grid cell executed by Runge-Kutta method. More such steps (i.e. at small values of integration step) result in smother, more precise, stream lines. Small number of steps (i.e. large integration steps) result in coarse steam flow representation. The value also determines the minimum distance of how close the streamline can approach the surface boundaries of construction. Default: 0.1 mm |
Max. propagation length | This number affects the number of integration steps of the
Runge-Kutta method performed from the starting point until iterations, and
thus tracking the stream field, are aborted. This number is important by defining the highest allowed total length of each separate streamline in millimetres. High values of maximum propagation length will obviously increase the computational time required to create the streamline. |
Terminal stream density | This number defines the magnitude of stream density
(modulus of flux vector) below which the tracking of the stream
field by Runge-Kutta method shall be aborted. Default: 0 |
Tube Radius | The streamline is shown as a tube to better emphasize the
stream (compared to single pixel thick line). The radius is entered in units
of the coordinate system - i.e. millimetres. Setting the tube radius = 0 will show it as simple line. Default: The initial value of tube radius is computed based on median extent of component (1/200 of it). Remark: The number of sides rendered for the tube can be adjusted within application settings. |
Start at:
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The position of staring point is defined by the
intersection of the three slice planes
Slice-X / Slice-Y / Slice-Z or, for 2 dimensional models, one can chose to automatically generate starting points on space boundaries at equidistant intervals of heat stream. Remark: The "Start at Space Boundary" option is available for 2D projects only. |
Space Boundary |
The name of the space from which the streamlines shall be drawn |
# intervals | Number if intervals the stream function calculated at the
space boundary shall be divided into thus determining the starting points
for streamline generation. Remark: High number of streamlines generated will result in high graphical memory demand. It is advised to set the tube radius to 0. Remark: If the stream flows to the space and (at other section of the space boundary) from the space, the highest amount is taken and divided into intervals. To visualize the dividing line between the areas of stream loss and stream win select division at 1 interval only. |
Remark: Because streamline (the flow) exists in model's
interior only it is advisable to either turn the view of the surface
completely off or show it partially transparent (i.e.
not opaque) or show it as
wireframe only. The same applies to the visibility of
slice planes X, Y, Z (starting
point of stream tracing) which shall be made partly transparent or
even completely invisible (Opacity = 0).
The tooltip of the tab will show up if the surface
obscures objects rendered within the interior of the model.
Remark: When surface humidity is selected as active function (panel General), the streamline is coloured grey only, because the function of surface humidity is defined at component's surface only.
Remark: Current implementation of the solution of the
initial boundary problem posed here uses Runge-Kutta method of fourth order with
adaptive step control. The boundary condition of step control is set to the
small, still numerically stable, error value of epsilon = 10-17
and cannot be changed by the user.
The initial-, minimal- and maximal integration steps are determined by the user (Integration
Step length).
The minimal step corresponds to the value entered
(default 0.1 mm). The initial step length is 100 times the minimal value.
The maximal step length is 10000 times the minimal value.
The
maximal propagation length corresponds
to the total length of the resulting streamline in millimetres.
Remark: Not to overwhelm the capacity of today's hardware equipment when combined with tube visualization following restrictions apply and are automatically checked and set:
Showing the streamline as Tube will be suspended (and all streamlines shown only as simple lines) when for all streamlines taken together the overall number of vertices needed for the tube representation would exceed 1.6 millions (i.e. number of segments < 1.6Mio/NumberOfTubeSides).
Rendering as tube will be suspended for all streamlines also also if any part of any streamline themselves would contain more than 100.000 segments - such too long streamline, then shown by simple lines, will show broken early. This applies to both parts (the forward and backward) of each separate streamline independently.
Remark:
Start at – Probe X/Y/Z: The position of staring point of a
streamline is defined by the intersection of the three
slice planes
Slice-X / Slice-Y / Slice-Z. The
intersection of the three planes must be within model's interior.
If the intersection of the slices X/Y/Z (we call it the probe point) is located
very close to components surface it might happen that no stream line can be
started from there.
Shall this (rare) situation arise you will have to shift the starting point by
at least the half of the smallest size of the fine grid cells (i.e. the
start
thickness of the fine grid parameters, typically 0.5mm or 1mm).
Remark: Start at – Space Boundary: Produces many streamlines started at
selected space boundary. The application calculates the sum of stream flowing to
the space and the sum of stream leaving the space through the boundary (for
exterior space, case with two spaces without powers sources one of this values
is always 0). The sum with the largest modulus is divided into the number of
intervals entered (maximum 200 intervals, i.e. at 0.5% of the heat stream).
Along the space boundary the application repeats the calculation of the stream
function and places start points for the streamline at interval boundary values
calculated earlier (interpolated). To ensure, that every streamline will start
each starting point is shifted towards the interior of the model by about the half
thickness of the surface fine grind cell (typically 0.5mm or 1mm).
See also: Results 3D window, Active (settings), Opaque and Opacity (setting), Colorize (setting), Solid or Wireframe (setting), General (control panel), Active Function, Isolines (Isotherms), Slice X,Y,Z (control panel), Surface (control panel), Vectors (HedgeHog, Arrows) (control panel)
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